The proposed research is directed toward the study of regulation of expression of a set of coordinately functioning, housekeeping genes, namely, the ribosomal-protein (r-protein) genes. First, we plan the further investigation, of r-protein gene expression both at the translational and transcriptional levels, at the time of the first induction of r-protein synthesis during the normal developmental sequence of Drosophila embryogenesis. We have previously observed the uncoupling of r-protein and rRNA synthesis at early stages of development. We plan to explore the contributions of stored, maternally donated mRNAs and embryo encoded gene expression to this uncoupling phenomenon. These results will contribute to our understanding of the effect of embryo gene expression on metabolism during early development. Second, we plan to study the control of r-protein gene expression under "naturally occurring" conditions of lowered or absent ribosome biosynthesis. These conditions include response to stress, such as heat shock, and mutant strains deleted for rRNA genes. This work should provide insight into the "naturally occuring", as compared to drug-induced, responses of r-protein genes when there is an imbalance of one or more ribosome components. Finally, we plan to examine the chromosomal loation and sequence arrangement of one or more of the r-protein genes including mapping the sizes of their transcription units. In total, the results of these studies will be used to evaluate the coordination or non-coordinate expression of the various r-protein genes in conjunction with that of the rRNAs with a view toward understanding the molecular basis for regulation of this set of essential and ubiquitously expressed protein genes in a eukaryote.